Servicing Trailer Wheel Bearings

Boat Maintenance & Safety

Reviewed: January 2009

Author: Adam Robinson

Boating Review:

Service trailer wheel bearings, for safety’s sake.

Read more Boat Maintenance & Safety Tips.

Servicing Trailer Wheels for Safety – Boating Article by Modern Boating

“Service Trailer Wheel Bearings – Greasy does it!”

The advantage of trailer boating comes at the cost of maintenance, with wheel bearings commonly neglected.  Chances are, your trailer’s wheel bearings are immersed in water and grease right now. Bearings rust quickly, causing friction and heat when towing.  When submerged at the ramp, hot rotors cool rapidly, drawing water in, hastening the demise of bearings.

Single-axle trailers are at the greatest risk of a catastrophic road accident.  If the bearing fails, the
driver is unlikely to know until the wheel departs or the axle snaps.  So consider servicing your wheel
bearings at least annually.  Do so as follows:

Remove the wheel, then the bearing end cap and split pin, and brake assembly, if fitted (Pic 1).  Then remove the nut, washer, outer bearing cone and the entire rotor assembly (Pic 2).  Supporting the rotor
assembly, tap the inner seal free of the hub. Use mild tools to avoid damage (Pic 3).  The inner bearing cone should fall free.

Clean and inspect the axle spindle for damage.  Failed bearings can chew through axles, causing major
damage—not an easy roadside fix. A light marine grease coating will aid re-installation (Pic 4).

Remove bearing cups with a mild steel bar and hammer (Pic 5).  Screwdrivers are too hard and will damage the inside of the hub.  Beware, this can be a very difficult step requiring many carefully delivered blows to move the cups even the slightest amount.  You can expect to burr the inside of your hubs somewhat, causing cosmetic damage.  Consider omitting this step, leaving the old cups in place and replacing the bearing cones.

New cups can be seated using the old cups to drive them straight into the hub (Pic 6). Use the mild steel bar to drive them further.  Even more care is required here; damaged cups cause early bearing failure. ‘Cup drivers’ are available from specialty bearing shops for this task.

Fully pack bearing cones with grease (Pic 7).  ‘Grease packers’, again from a specialty bearing shop, do the job perfectly.  Pack the cleaned hub two thirds full of marine grease before installing the inner bearing cone.

Push the inner seal into place (Pic 8) before the hub assembly is replaced on the axle spindle, followed by the outer bearing cone. Replace the washer and nut.  Tighten the nut with a large spanner while turning the rotor, until it becomes difficult to move.  Back the nut off around a quarter turn and secure with a new split pin.  Finally, replace the bearing end cap.

After a short tow, check the temperature of the hub by hand.  Newly packed hubs should tow cool. If not, consider loosening the nut another quarter turn.

Review supplied by Modern Boating

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